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Ceratosaurus
Ceratosaurus was a medium sized carnivorous dinosaur with a unique horn protruding out of the end of its skull. Information Uniquely among theropods, Ceratosaurus possessed small, elongated, and irregularly formed osteoderms (skin bones) along the midline of its body. Such osteoderms have been found above the neural spines of cervical vertebrae 4 and 5, as well as caudal vertebrae 4 to 10, and probably formed a continuous row that might have extended from the base of the skull to most of the tail. As suggested by Gilmore in 1920, their position in the rock matrix likely reflects their exact position in the living animal. The osteoderms above the tail were found separated from the neural spines by 25 millimeters to 38 millimeters, possibly accounting for skin and muscles present in between, while those of the neck were much closer to the neural spines. Apart from the body midline, the skin contained additional osteoderms, as indicated by a 58 millimeters by 70 millimeters large, roughly quadrangular plate found together with the holotype; the position of this plate on the body is unknown. Specimen UMNH VP 5278 was also found with a number of osteoderms, which have been described as amorphous in shape. Although most of these ossicles were found at most 5 m apart from the skeleton, they were not directly associated with any vertebrae, unlike in the C. nasicornis holotype, so their original position on the body cannot be inferred from this specimen. The most distinctive feature was a prominent horn situated on the skull midline behind the bony nostrils, which was formed from fused protuberances of the left and right nasal bones. Only the bony horn core is known from fossils—in the living animal, this core would have supported a keratinous sheath. While the base of the horn core was smooth, its upper two-thirds were wrinkled and lined with groves that would have contained blood vessels when alive. In the holotype, the horn core is 13 centimeters long and 2 centimeters wide at its base, but quickly narrows to only 1.2 centimeters further up; it is 7 centimeters in height. It is longer and lower in the skull of MWC 1. In the living animal, the horn would likely have been more elongated due to its keratinous sheath. Behind the nasal horn, the nasal bones formed an oval groove; both this groove and the nasal horn serve as features to distinguish Ceratosaurus from related genera. In addition to the large nasal horn, Ceratosaurus possessed smaller, semicircular, bony ridges in front of each eye, similar to those of Allosaurus. These ridges were formed by the lacrimal bones. In juveniles, all three horns were smaller than in adults, and the two halves of the nasal horn core were not yet fused. In 1884, Marsh considered the nasal horn of Ceratosaurus to be a "most powerful weapon" for both offensive and defensive purposes, and Gilmore, in 1920, concurred with this interpretation. The use of the horn as a weapon is now generally considered unlikely, however. In 1985, David Norman believed that the horn was "probably not for protection against other predators," but might instead have been used for intraspecific combat among male ceratosaurs contending for breeding rights. Gregory S. Paul, in 1988, suggested a similar function, and illustrated two Ceratosaurus engaged in a nonlethal butting contest. In 1990, Rowe and Gauthier went further, suggesting that the nasal horn of Ceratosaurus was "probably used for display purposes alone" and played no role in physical confrontations. If used for display,the horn likely would have been brightly colored. A display function was also proposed for the row of osteoderms running down the body midline. The strongly shortened metacarpals and phalanges of Ceratosaurus raise the question whether the manus retained the grasping function assumed for other basal theropods. Within the Ceratosauria, an even more extreme manus reduction can be observed in abelisaurids, where the fore limb lost its original function, and in Limusaurus. In a 2016 paper on the anatomy of the Ceratosaurus manus, Carrano and Jonah Choiniere stressed the great morphological similarity of the manus with those of other basal theropods, suggesting that it still fulfilled its original grasping function, despite its shortening. Although only the first phalanges are preserved, the second phalanges would have been mobile, as indicated by the well-developed articular surfaces, and the digits would likely have allowed a similar degree of motion as in other basal theropods. As in other theropods other than abelisaurids, digit I would have been slightly turned in when flexed. In-Game Ceratosaurus will be in the early access of Prehistoric Kingdom. Gallery HJFcipE.jpg Ceratosaurus_01_Preview.png|Sunburst Ceratosaurus_02_Preview.png|Savannah Ceratosaurus_03_Preview.png|Jade Category:Theropod Category:Dinosaurs Category:Carnivore